1. Field of the Invention
The present invention relates to a closed compressor which is to be connected to aluminum pipes in a refrigerator or an air conditioner.
2. Description of Related Art
Air conditioners incorporated into automotive vehicles generally employ R-12 refrigerant and an open compressor. Because such air conditioners are required to be lightweight, aluminum is generally used for a shell of the compressor and connecting pipes.
Nowadays, however, automotive vehicles require a closed compressor for the purpose of avoiding atmospheric pollution by the refrigerant.
FIG. 3 depicts a typical closed compressor currently used in a room air conditioner.
The compressor shown in FIG. 3 has a closed vessel 104 made up of a cylindrical shell 101, an upper shell 102, and a lower shell 103, all of which are made of steel. The upper and lower shells 102 and 103 are seam-welded to the cylindrical shell 101 to meet hermetical sealing requirements and to provide resistance to pressure. The closed vessel 104 accommodates an electric motor 105 and a compression element assembly 106 driven by the electric motor 105.
Refrigerant compressed by the compression element assembly 106 is discharged into the closed vessel 104, which has sufficient resistance to the pressure of the discharged refrigerant because it is made of steel.
The cylindrical steel shell 101 has an external suction copper pipe 107 joined thereto by silver-brazing. The suction pipe 107 is joined to a vapor-liquid separator 108 via a connecting pipe 110. The vapor-liquid separator 108 is made of iron or copper and has a suction copper pipe 109 through which the refrigerant is introduced thereinto. The refrigerant which has passed through the vapor-liquid separator 108 is introduced into the closed vessel 104 through the connecting pipe 110, which is joined to the vapor-liquid separator 108 by silver-brazing or copper-brazing.
The closed compressor of the above-described construction is incorporated into the room air conditioner and is connected to a heat exchanger (not shown) via connecting pipes 111a and 111b. Because the connecting pipes 111a and 111b are generally made of copper, they are joined to the suction pipe 109 and to a discharge pipe 112 secured to the upper shell 102, respectively, by copper-brazing or the like.
However, the following problems are encountered in utilizing the closed compressor in an automotive air conditioner.
In order to reduce the weight of the automotive vehicle, the compressor is connected to the heat exchanger generally by lightweight aluminum pipes in a comparatively small engine room. Accordingly, brazing is considerably difficult which is employed for pipe connections in the room air conditioner, as discussed above.
Furthermore, if copper pipes are employed as connecting pipes joined to the compressor, it is necessary to connect them with aluminum pipes leading to the heat exchanger. Because ionization tendency greatly differs between copper and aluminum, it is likely that electrolytic corrosion would occur.